What It Takes to Get Teens Moving

"You can build beautiful parks and facilities; but if children don't have friends to play with, these facilities won't be enough to increase their physical activity," said study lead author Sarah-Jeanne Salvy.

"Peers and friends are the catalyst of the physical environment," Salvy added. She is an associate professor in the division of preventive medicine at the University of Alabama at Birmingham.

For the study, Salvy and her colleagues followed 80 teens who wore devices that measured their activity levels for seven consecutive days.

Time spent with friends and peers affected the link between the teens' beliefs about neighborhood safety and physical activity. Specifically, the association between concerns about neighborhood safety and physical activity were stronger among teens who spent little time with friends than among those who spent more time with friends.

"Studies of neighborhood safety and physical activity have typically neglected to consider the youth's peer context as a modifier of these relationships," Salvy said in a university news release.

"This study fills this gap in testing the independent and interactive effects of both perceived neighborhood safety and time spent with friends and peers on young adolescents' physical activity and sedentary behavior," she added.

"Our findings emphasize the importance of considering social factors when examining the impact of neighborhood on physical activity," Salvy said.

The study was published online in the journal Preventive Medicine Reports.